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Abstract The co-sensitization of mesoscopic TiO 2 anode is a promising solution to wide-spectra dye-sensitized solar cells (DSSCs) with improved power conversion efficiency. Quantum dots are featured with tunable bandgaps, small sizes and high absorption coefficients, therefore they are always combined with state-of-the-art organic dyes for co-sensitized solar cells. We present here the sonochemistry-assisted synthesis of hybrid black/red phosphorus quantum dots (BP/RPQDs) for DSSC applications. The preliminary results demonstrate that hybrid BP/RPQDs have prolonged recombination lifetime of photogenerated carriers and light-response from ultraviolet to visible and even near-infrared (NIR) region. Upon assembly into liquid-junction DSSCs, the devices with BP/RPQDs-only and BP/RPQDs-N719 co-sensitizer achieve efficiencies of 0.12% and 8.02% in comparison with 7.60% for N719-only solar cell. Using photofluorescent photoanode from mesoscopic TiO 2 and long-persistence phosphor (LPP), the new-typed DSSC presents persistent power generation performances after ceasing simulated sunlight irradiation. Graphical abstract Image 1 Highlights • Hybrid BP/RPQDs are made by a sonochemistry-assisted method. • The hybrid BP/RPQDs show wide light-response in light-harvesters of DSSCs. • BP/RPQDs-only solar cells show a PCE of 0.12%. • An efficiency as high as 8.02% is achieved for BP/RPQDs tailored DSSCs. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSC) have narrow spectral response and serious electron-hole recombination, which are two burdens for photovoltaic performance enhancement. In order to make high-performance DSSCs featured by wide-spectral absorption and fast charge extraction, we present here experimental realization of co-sensitization of nitrogen (N)-doped carbon quantum dots (N-CQDs) with N719 dye. Arising from up-conversion and hole extraction behaviors of N-CQDs, a maximized power conversion efficiency (PCE) as high as 9.29% under one sun illumination is achieved for N 300 -CQDs/N719 co-sensitized DSSC in comparison with 8.09% for N 300 -CQDs-free device. Due to light storing and emitting characteristics of photofluorescent long persistence phosphors in mesoscopic titanium dioxide/long persistence phosphor ( m -TiO 2 /LPP) photoanode, electricity is persistently generated when ceasing sunlight illumination. This work is far from optimization, but the physical proof-of-concept co-sensitization and fast charge extraction may remarkably widen light-response windows and promote electron-hole separation for advanced photovoltaic devices. [ABSTRACT FROM AUTHOR]

Photovoltaics are regarded as the promising solution to resolve energy and environmental problems owing to their high power conversion efficiency and zero emissions. However, the narrow-spectra absorption range and serious recombination reactions at electrode/electrolyte interfaces are two major drawbacks for high-performance solar cells. Herein, a new way of synthesizing organic-inorganic hybrid CH 3 NH 3 PbX 3 (X = Cl, Br or I) perovskite quantum dots (PQDs) is demonstrated by dropping perovskite precursor solution into anhydrous toluene. After a systematic study, the results demonstrate that the energy levels of PQDs can be tuned through optimizing the stoichiometric ratio of halide ions, showing good optical properties for photovoltaic applications. A quasi-solid-state sensitized solar cell with configuration of FTO/ m -TiO 2 /PQDs/dye/long persistence phosphor/gel electrolyte/Pt/FTO is fabricated, yielding an impressive power conversion efficiency as high as 7.91%, which is higher than 7.26% for referenced device free of PQDs. The improved performances are mainly attributed to the increased light absorption as well as reduced recombination upon the incorporation of PQDs and long persistence phosphor into devices. [ABSTRACT FROM AUTHOR]

Bifacial light-harvesting technology is regarded as one effective strategy to enhance the power output of photovoltaic devices, in which the transparent electrode is crucial to determine the power conversion efficiency when illuminated from rear side. To date, the efficiency enhancement of the state-of-the-art bifacial mesoscopic solar cells is mainly focused on the rational design of high catalytic counter electrode without sacrificing the transparency. The cell performance maximum through increasing electron density at counter electrode surface to enhance its catalytic ability is still a challenging problem. In the current work, bi-tandem carbon quantum dots are made to tailor transparent CoSe counter electrode for bifacial dye-sensitized solar cells, achieving a maximized front power conversion efficiency of 8.54% and a rear efficiency of 6.55% in comparison with 7.87% and 5.03% for carbon quantum dots-free device, respectively. The mechanism behind this increment is stemmed from the photo-excited electrons of bi-tandem carbon quantum dots and therefore realizing the electron accumulation on the counter electrode surface. [ABSTRACT FROM AUTHOR]

Bifacial photovoltaics are promising devices for significantly harvesting solar energy and generating power from either front or rear side. We present here the fabrication of new category of high-performance bifacial dye-sensitized solar cells (DSSCs) tailored with transparent S-doped carbon quantum dots (S-CQDs)/metal selenide counter electrodes. Arising from photoexcitation of S-CQDs and therefore increased electron density at electrode surfaces, the catalytic ability of S-CQDs tailored counter electrodes is markedly enhanced under solar irradiation. The bifacial DSSCs yield maximized front and rear efficiencies of 9.15% and 6.26%, respectively. [ABSTRACT FROM AUTHOR]

Development of high-performance light harvesters is a persistent goal for mesoscopic solar cells. In the current work, lead-free CH 3 NH 3 SnBr 3-x I x (x = 0–3) perovskite quantum dots (QDs) are made by integrating Br − ions into host crystal structure. Through tuning Br/I ratio, these perovskite-structured QDs are highlighted with tunable optical bandgaps. When applied as light harvesters for mesoscopic solar cell applications, the devices yield reasonable power conversion efficiency and rapid start-up behaviors. An efficiency of 8.79% is achieved for CH 3 NH 3 SnBr 3-x I x QDs and N719 co-sensitized mesoscopic solar cells. [ABSTRACT FROM AUTHOR]